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Piecewise linearisation is the normal technique - take a look at https://www.hindawi.com/journals/mpe/2013/101376/

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Dear Patrick

I uploaded a pdf file please have a look again

Dear Kjetil,

Thank you for your comment I will go through it

Hello dear Araz, 

Here's a trick that can help  if you want to make the product of two variables x and y linear : 

You define a new variable zxy  such as : 

zxy >= x+y-1

zxy 

Sarah Bounejmate's trick works a little better I believe if you instead of zxy

Another possibility in case of bounded variables is to use a polytopic model, i.e., if x belongs to [a, b] and y belongs to [c, d], then the function xy is mapped to a polytope that is a linear combination whose coefficients depend on the mapped vertexes.

Dear Luis,

Truncation of the Taylor series expansion around certain point gives a linear model. This model is different from the polytope model that is also linear. The first one is a good approximation around the given point and the second one leads to linear combinations inside the polytope.  

Regards,

René Galindo